Magnetic Induction for In-situ Healing of Polymeric Material

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Abstract

The field of self-healing materials is growing dramatically due to the obvious in- centive of having structural materials with the ability to repair damage. Some polymers have demonstrated the ability to heal from damage autonomously[12, 26], when exposed to heat[1], or when punctured[5, 9]. The goal of this research is to develop a "proof-of-concept" polymer composite that has the ability to heal when exposed to an alternating magnetic field.
Several types of magnetic particulate were inspected for use in the production of polymer composite test samples. The types of particulate used in sample production were two supplies of γ-Fe₂O₃, one supply of α-Fe₂O₃, and one supply of Ni-Zn Ferrite. Surlyn 8940 was selected as the bulk polymer due to its self-healing qualities[9]. A method for melt mixing the particulate with the polymer in various volume fractions was developed and an SEM was used to study the dispersion of the particulate.
Once the polymer composite samples were made, various tests were conducted to characterize the samples in order to determine what effects the particulate had on the prop- erties of the bulk polymer. These tests included differential scanning calorimetry (DSC), rheology, conductivity, and magnetic response. Once the samples were characterized, tests were performed to study the composite polymers ability to heat and heal. These tests included healing microscopy, induction heating, and tensile testing. From this study, it was found that the addition of particulate to the bulk polymer does alter the properties by increasing viscosity and electrical conductivity.
However, the addition of particulate does not change the melt temperature, but allows the magnetic hysteresis loop of each composite sample to be revealed through magnetic testing. Through healing microscopy and tensile testing, the polymer composites were found to heal when heated, but at a higher temperature than the pure bulk polymer samples. Each type of polymer composite also heated to varying degrees through magnetic induction. Due to the ability of the polymer composite to heal and heat, a "proof-of-concept" has been provided for a magnetically healing polymer composite.